function setTall() {
	if (document.getElementById) { // Do you know the DOM?
		// specify columns
		var divs = new Array(	document.getElementById('leftCol'), 
								document.getElementById('mainContent'),
								document.getElementById('right')
		);
		
		var maxHeight = 0;

		// reset the height
		for (var i = 0; i < divs.length; i++) { // Get the height of the tallest column
			divs[i].style.height = 'auto';
		}
		
		for (var i = 0; i < divs.length; i++) { // Get the height of the tallest column
			if( i == 0 ) { // small hack for the absolute positioned adres div
				maxHeight = divs[i].offsetHeight + document.getElementById('adres').offsetHeight;
			} else {
				if (divs[i].offsetHeight > maxHeight) maxHeight = divs[i].offsetHeight;
			}
		}

		for (var i = 0; i < divs.length; i++) { // Loop through columns
			divs[i].style.height = maxHeight + 'px'; // Set the height of column
			if (divs[i].offsetHeight > maxHeight) { // is the size of the column correct?
				// correct padding/margin if needed
				divs[i].style.height = (maxHeight - (divs[i].offsetHeight - maxHeight)) + 'px';
			}
		}

	}
}

window.onload = function() {
	setTall();
}